US4542991A - Mixing silo for pneumatically homogenizing fine-grained or dust-like material - Google Patents

Mixing silo for pneumatically homogenizing fine-grained or dust-like material Download PDF

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Publication number
US4542991A
US4542991A US06/559,421 US55942183A US4542991A US 4542991 A US4542991 A US 4542991A US 55942183 A US55942183 A US 55942183A US 4542991 A US4542991 A US 4542991A
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Prior art keywords
silo
zones
heavily
aerated
weakly
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Expired - Fee Related
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US06/559,421
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English (en)
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Werner Krauss
Heinrich Vogt
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Claudius Peters AG
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Claudius Peters AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F33/00—Other mixers; Mixing plants; Combinations of mixers
    • B01F33/40—Mixers using gas or liquid agitation, e.g. with air supply tubes
    • B01F33/406—Mixers using gas or liquid agitation, e.g. with air supply tubes in receptacles with gas supply only at the bottom
    • B01F33/4062—Mixers using gas or liquid agitation, e.g. with air supply tubes in receptacles with gas supply only at the bottom with means for modifying the gas pressure or for supplying gas at different pressures or in different volumes at different parts of the bottom

Definitions

  • the invention concerns a mixing silo for pneumatically homogenizing fine-grained or dust-like material, the bottom of which has groups of aeration zones which can be alternately supplied with compressed air and operated in such a manner that in each group a bottom zone partially limited by the outer limit of the silo bottom is heavily aerated and a bottom zone located between the heavily aerated bottom zones is aerated only weakly, and the outlet of which is located outside of the silo bottom.
  • a high-grade mixing method in which the loose material contained in a silo and fluidized by aeration is circulated by allowing it to rise over a heavily aerated bottom zone and to drop down over another, more weakly aerated bottom zone is designated as pneumatic homogenizing (German AS No. 1 138 608). Since homogenizing silos set up for circulating the entire silo contents require a lot of energy, mixing chamber silos (German AS No. 15 07 888) in conjunction with mixing bed apparatuses in front are often preferred, whereby the long-term adjustment of the silo contents depends primarily on mixing by gravity. However, mixing bed apparatuses are also very expensive.
  • the invention has the task of creating a silo of the type initially described which achieves a good homogenization with little expenditure of energy.
  • the solution of the invention consists of the fact that the exclusively weakly aeratable bottom zone separates the heavily aeratable bottom zones from each other in a star pattern and that the outlet is constructed as an overflow.
  • the invention provides that the heavily aeratable bottom zone is surrounded where it is not limited by the silo wall on all sides by weakly aeratable bottom zones.
  • the frictional resistance of dead masses of material which limit the moved spatial volume on both sides does not have to be overcome in this movement.
  • Non-aerated material is located in this instance exclusively at those limiting surfaces of the moved area of material where the material drops down over the weakly aerated zone.
  • the invention also has the advantage that the loosening air is not lost through the opening of the material outlet near the bottom, where the critical horizontal movement from the weakly aerated to the heavily aerated zone occurs.
  • the material outlet can be positioned outside of the actual aeration surface (German patent No. 11 52 876); in this instance, however, it is provided near the bottom in the silo wall or in a bottom part extended out via an opening in the silo wall.
  • Said compact cross-sectional shaping of the spatial part subjected in accordance with the invention to a mixing movement contradicts a rule which has generally been observed in the past, namely, that a satisfactory circulating movement can only occur in a partial area of the silo if the ratio of the height to the diameter of the spatial part subjected to the mixing movement is not greater than approximately 1.5 to a maximum of 2. If the mixing space is too narrow in relation to its height, the downward movement of the material over the more weakly aerated zones is impeded by the material which is vehemently flowing up due to the heavy aeration, with the consequence that only a type of bubbling turbulence occurs and not a circulatory movement.
  • the material over adjacent bottom zones which were previously alternatingly aerated also has a certain flowability due to the preceeding aeration which allows it to participate in the sinking movement. Therefore, the volumetric part in the mixing area which participates in the mixing movement has a greater transversal extent than the bottom zones employed for its aeration do.
  • the weakly aerated zones associated with the individual groups should not be separated from each other. This expression means that they should essentially be directly adjacent to each other or even overlap each other. Overlap in this connection means that a certain zone belongs to two separately operated aeration groups and is therefore always aerated when the one or the other group is operated. However, such an overlapping has generally proven to be not necessary.
  • the overflow system also assures that only mixed material reaches the outlet. There is no short circuit between the newly added mterial to be mixed and the outlet, because the material raised over the heavily aerated zone to the surface of the material flows down laterally to the zones which are aerated only weakly or not at all, carrying along with it the freshly added material, which is directed away from the outlet.
  • the material to be mixed can be added centrally.
  • Known distributing devices can be provided over the cross section of the discharge for a more even distribution.
  • the ratio of the fill height to the diameter of the silo chamber is advantageously between 1 to 1.5, as is known from customary homogenizing silos which are fully fluidized.
  • the homogenizing silo of the invention should have a lower shift rate which should not be greater than 10 and preferably not greater than 6 minutes in order to assure that the material located in the vicinity of the particular zone being weakly aerated is still sufficiently movable to be able to participate in the sinking movement.
  • FIG. 1 shows a top view of the silo bottom.
  • FIG. 2 shows a vertical longitudinal section through a two-story silo whose upper silo part is constructed in accordance with the invention.
  • the silo part 4 of the invention which has cylindrical walls 5 and bottom 6 with aerating devices 7, is located on a lower silo part 1 which has bottom 2 and cylindrical wall 3 and is constructed as a storage silo.
  • Bottom 6 is slightly inclined toward the center, where outlet opening 8 for emptying mixing silo 4 into storage silo 1 is located.
  • outlet opening 8 is closed.
  • the material to be mixed can be fed into mixing silo 4 through central opening 9 in the top 10, which can be connected to a baffle plate 11 for better distribution.
  • Filter 12 with suction blower 13 for removing loosening air is located on silo top 10.
  • aeration devices 7 of the silo bottom are arranged in the form of four quadrant-like aeration fields which form one of the above groups.
  • Each one is divided into a heavily aerated zone 14 and a more weakly aerated zone 15 which are distinguished from one another in the lower right field by different shadings.
  • Heavily aerated zone 14 projects from the circumference into the aeration field.
  • the weakly aerated zone surrounds the heavily aerated zone in an angle pattern on its side which faces the center and the other fields.
  • the ratio of the surface areas of the heavily aerated zones and of the weakly aerated zones is on the order of approximately 1:2 to 1:4.
  • the heavily aerated zones 14 of each aeration field are connected over lines 16 with solenoid valves 17 and over line 18 to a first blower 19, while the more weakly aerated zones 15 of each field are connected over lines 20 and 21 and solenoid valves 22 to a second blower 23.
  • Blower 19 can supply air to any heavily aerated zone 14 and blower 23 can supply air to any weakly aerated zone 15.
  • the solenoid valves are controlled in time in such a manner that only zones 14 and 15 of any one aeration field are in operation at a time, e.g. for a period of 5 minutes. Then, they are switched in such a manner that each aeration field is alternatingly actuated in a rotating pattern or in some other pattern.
  • Each heavily aerated zone 14 contains a vertical overflow pipe 24 near silo wall 5 whose entrance opening is located at the height of the desired fill level in the case of fluidized material.
  • Overflow pipes 24 can be provided with closing parts which are regulated in coincidence with the change of the aeration fields. This is, however, usually not necessary, because, as is indicated in FIG. 2, the fill level over the zone which is being heavily aerated is higher than the fill level over the other zones, so that opening 25 of overflow pipe 24 is reached only here, while the openings of the other overflow pipes lie higher. While the material in the overflow pipe 24 associated with the particular aeration field in operation flows downward, as is indicated in FIG. 2, the other overflow pipes permit a counterflow of air from storage silo 1 into the upper chamber of mixing silo 4.
  • the expansion of the material over the heavily aerated zone causes homogenized material on the surface to flow from the active guadrant over the unaerated quadrants.
  • the invention makes the best possible use of this vertical and horizontal flowing of the loose material from one quadrant into the adjacent quadrant by switching much more frequently from the aeration of one quadrant to the next than is the case with known, fully fluidized quadrant homogenizing silos. While in the latter an aeration state was retained long enough to bring about a multiple circulation, in the case of the invention the shift time can be reduced so sharply that only a partial circulation occurs.
  • the silo of the invention can be operated continuously and yet be large enough to receive the grinding output of a time period, e.g. 8 hours, necessary to compensate long-lasting variations in composition.
  • the silo of the invention also requires little maintenance, as it has a simple construction and the expenditure for monitoring and for transport devices is small.
  • the aeration in the quadrants not in operation is generally completely cut off. It can, however, be advantageous in special instances to aerate them weakly too; however, they are aerated so much more weakly than even the weakly aerated zones of the particular quadrant in operation that as regards the circulating function they can be considered as not being aerated.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Storage Of Harvested Produce (AREA)
  • Apparatuses For Bulk Treatment Of Fruits And Vegetables And Apparatuses For Preparing Feeds (AREA)
US06/559,421 1982-12-09 1983-12-08 Mixing silo for pneumatically homogenizing fine-grained or dust-like material Expired - Fee Related US4542991A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19823245542 DE3245542A1 (de) 1982-12-09 1982-12-09 Mischsilo
DE3245542 1982-12-09

Publications (1)

Publication Number Publication Date
US4542991A true US4542991A (en) 1985-09-24

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ID=6180198

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US06/559,421 Expired - Fee Related US4542991A (en) 1982-12-09 1983-12-08 Mixing silo for pneumatically homogenizing fine-grained or dust-like material

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US (1) US4542991A (da)
EP (1) EP0111294B1 (da)
BR (1) BR8306783A (da)
DE (2) DE3245542A1 (da)
DK (1) DK157835C (da)
ES (1) ES284574Y (da)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4834544A (en) * 1987-07-06 1989-05-30 Fuller Company Fines separation system for pellet blender
US6138377A (en) * 1999-07-21 2000-10-31 United States Gypsum Company Apparatus and process for cooling and de-steaming calcined stucco
GB2384161A (en) * 2001-12-04 2003-07-23 Powder Conditioning Ltd Conditioning powders
WO2004076048A1 (en) * 2003-02-28 2004-09-10 Degussa Ag Homogenisation of nanoscale powders
US20060067160A1 (en) * 2004-09-30 2006-03-30 Koetas Joseph P Apparatus for forming a polishing pad having a reduced striations
US20080063495A1 (en) * 2006-09-08 2008-03-13 Carsten Niedworok Method of Filling Large-Capacity Storage Silos With a Fluidizable Material, and Arrangement Therefor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3516014A1 (de) * 1985-05-03 1986-11-06 Claudius Peters Ag, 2000 Hamburg Misch- und lagersilo

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3653639A (en) * 1971-02-04 1972-04-04 Whirl Air Flow Corp High pressure air and liquid blending method and apparatus for discrete materials
US3656717A (en) * 1969-08-28 1972-04-18 Polysius Ag Process and apparatus for the continuous pneumatic treatment of fine material
US4239421A (en) * 1976-12-18 1980-12-16 Claudius Peters Ag Vertical silo for fluid bulk material with an inner blending chamber
US4364665A (en) * 1979-12-11 1982-12-21 Krupp Polysius Ag Storage and mixing silo for bulk material
US4375335A (en) * 1977-06-30 1983-03-01 Klein Albenhausen Heinrich Silo combination for mixing stored material
US4472062A (en) * 1981-11-02 1984-09-18 Krupp Polysius Ag Continuous mixing silo and method of operation

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD61194A (da) *
DE1027966B (de) * 1953-07-29 1958-04-10 Peters Ag Claudius Verfahren zum Mischen und Homogenisieren trockener pulveriger Stoffe auf teilweise pneumatischem Wege
DE1152876B (de) * 1958-05-20 1963-08-14 Fuller Co Verfahren und Vorrichtung zum Konditionieren, insbesondere Durchmischen von pulverfoermigem Material
DE1138608B (de) * 1960-09-07 1962-10-25 Peters Ag Claudius Verfahren und Einrichtung zum pneumatischen Mischen von staub-foermigem oder feinkoernigem trockenem Gut
FR1325873A (fr) * 1962-03-26 1963-05-03 Shell Int Research Procédé de mélange de matières en poudre
DE1906018A1 (de) * 1969-02-07 1970-09-03 Peters Ag Claudius Verfahren zum pneumatischen Mischen von staubfoermigem oder feinkoernigem Gut
DE2108418C3 (de) * 1971-02-22 1975-07-03 Polysius Ag, 4723 Neubeckum Verfahren zum pneumatischen Mischen und Homogenisieren
DE2223550A1 (de) * 1972-05-15 1973-12-06 Hans-Joachim Dipl-Ing Selig Querstromboden fuer homogenisierung rieselfaehiger schuettgueter
FR2261804A1 (en) * 1974-02-26 1975-09-19 Daloz Ets Homogenising dry powders in fluidised bed mixer - with several different fluidising conditions in adjacent sectors of the bed
DE2436414C2 (de) * 1974-07-29 1975-11-06 Claudius Peters Ag, 2000 Hamburg Verfahren zum Betrieb einer Vorrichtung zum Mischen von Schüttgut
DE3026472C2 (de) * 1980-07-12 1983-04-21 Claudius Peters Ag, 2000 Hamburg Verfahren zum Betrieb eines Schüttgutsilos

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3656717A (en) * 1969-08-28 1972-04-18 Polysius Ag Process and apparatus for the continuous pneumatic treatment of fine material
US3653639A (en) * 1971-02-04 1972-04-04 Whirl Air Flow Corp High pressure air and liquid blending method and apparatus for discrete materials
US4239421A (en) * 1976-12-18 1980-12-16 Claudius Peters Ag Vertical silo for fluid bulk material with an inner blending chamber
US4375335A (en) * 1977-06-30 1983-03-01 Klein Albenhausen Heinrich Silo combination for mixing stored material
US4364665A (en) * 1979-12-11 1982-12-21 Krupp Polysius Ag Storage and mixing silo for bulk material
US4472062A (en) * 1981-11-02 1984-09-18 Krupp Polysius Ag Continuous mixing silo and method of operation

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4834544A (en) * 1987-07-06 1989-05-30 Fuller Company Fines separation system for pellet blender
US6138377A (en) * 1999-07-21 2000-10-31 United States Gypsum Company Apparatus and process for cooling and de-steaming calcined stucco
GB2384161A (en) * 2001-12-04 2003-07-23 Powder Conditioning Ltd Conditioning powders
WO2004076048A1 (en) * 2003-02-28 2004-09-10 Degussa Ag Homogenisation of nanoscale powders
US20070253279A1 (en) * 2003-02-28 2007-11-01 Degussa Ag Homogenisation of Nanoscale Powders
US20060067160A1 (en) * 2004-09-30 2006-03-30 Koetas Joseph P Apparatus for forming a polishing pad having a reduced striations
US7275856B2 (en) * 2004-09-30 2007-10-02 Rohm And Haas Electronic Materials Cmp Holdings, Inc. Apparatus for forming a polishing pad having a reduced striations
US20080063495A1 (en) * 2006-09-08 2008-03-13 Carsten Niedworok Method of Filling Large-Capacity Storage Silos With a Fluidizable Material, and Arrangement Therefor
US8721230B2 (en) * 2006-09-08 2014-05-13 Ibau Hamburg Ingenieurgesellschaft Industriebau Mbh Method of filling large-capacity storage silos with a fluidizable material, and arrangement therefor

Also Published As

Publication number Publication date
DE3245542A1 (de) 1984-06-14
ES284574U (es) 1985-07-01
EP0111294B1 (de) 1987-08-12
ES284574Y (es) 1986-04-01
EP0111294A3 (en) 1985-07-03
DK157835B (da) 1990-02-26
DK157835C (da) 1990-08-06
BR8306783A (pt) 1984-07-17
DE3372925D1 (en) 1987-09-17
DK564683A (da) 1984-06-10
DK564683D0 (da) 1983-12-08
EP0111294A2 (de) 1984-06-20

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